My new signature:
My sisters can't call me crazy- they're related to my mom, too.
Ok, now for the origin. I was at a party, and we were talking about how our siblings perceive us. One person said that their older brother always calls them crazy. And I said, "Oh, well see, my sisters can't call me crazy- they're related to my mom, too." And then I thought, "ooh, that's going to be my next signature!" So there it is.